Impact compaction of loose materials

ABSTRACT

The specification discloses an impact roller which is attachable to a hauling vehicle via a drawbar and a resilient coupling and which includes restraining means, for example in the form of damping means or braking means, to restrain excessive relative horizontal movement between the roller and the drawbar during hauling of the roller.

United States Patent Berrange [451 May 16,1972

IMPACT COMPACTION OF LOOSE MATERIALS Aubrey Ralph Berrange, Pretoria,South Inventor:

Africa Assignee: South African Inventions Development Corporation,Pretoria, South Africa Filed: Mar. 19, 1970 Appl.No.: 21,016

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 2,909,106 10/1959 Berrange ..94/48 Primary Examiner.lacob L.Nackenofi- Attorney-Karl W. F locks 57 ABSTRACT The specificationdiscloses an impact roller which is attachable to a hauling vehicle viaa drawbar and a resilient coupling and which includes restraining means,for example in the form Apr. 2, 1969 South Africa ..69/2360 of dampingmeans or braking means to restrain excemve relative horizontal movementbetween the roller and the US. Cl ..94/48, 94/50 drawbar during haulingof the m Int. Cl v ..E0lc 19/30 Field of Search "94/50, 48 16 Claims, 5Drawing figures 56 u a u I; 54

PHENTEnm 1s m:

SHEET 3 OF 3 HEN:

IMPACT COMPACTION OF LOOSE MATERIALS BACKGROUND OF THE INVENTION Thisinvention relates to impact compaction of layers of soils and gravels.More particularly the invention relates to control means for controllingthe movement of an impact roller, to an improved impact roller and to amethod of controlling the movement of such a roller.

Impact rollers are rollers suitable for the compaction of materials suchas soils, gravels and the like by employing impact forces generated whensuch a roller is hauled across a surface.

In this specification an impact roller is to be understood as includinga roller having a profile of a non-circular multilobed cross-section.When such a roller is hauled across a surface, it rotates, therebycausing the center of gravity of the roller to rise and fall. Thevertical distance of rise or fall is known as the lift of the roller.During the fall of the center of gravity of the roller undergravitational force, impact is delivered to the underlying material inthe surface below the roller, thereby causing the material to becompacted.

The closest prior art known to the applicant is US. Pat. No. 2,909,106.

SUMMARY OF THE INVENTION According to the invention there is providedcontrol means for controlling the movement of an impact roller which isattachable to a hauling vehicle via a drawbar and a resilient couplingarranged to permit relative horizontal movement between the roller andthe drawbar, the control means including restraining means operablebetween the roller and the drawbar to restrain relative horizontalmovement between the roller and the drawbar.

Conveniently, the restraining means may be arranged to restrain relativehorizontal movement between the roller and the drawbar exceedingone-fourth to three-fourths of the lift of the roller.

If desired, the restraining means may be arranged to permitsubstantially unrestrained horizontal movement between the roller andthe drawbar, except for the influence of the resilient coupling, whenthe relative horizontal movement is less than one-fourth tothree-fourths of the lift of the roller.

The substantially unrestrained horizontal movement may be effected byproviding a lost motion coupling in the restraining means to permitinitial lost motion before the restraining means becomes effective.

The restraining means may in one form be arranged to damp relativehorizontal movement between the roller and the drawbar. In thisarrangement, the restraining means may include a plunger and cylinderassembly attachable between the roller and the drawbar, the plungerbeing arranged to partition the cylinder into two chambers and to bedisplaced in the cylinder by relative movement between the roller andthe drawbar to displace a fluid under pressure from one chamber of thecylinder to the other via a restricted orifice to damp the movement ofthe plunger in the cylinder.

In another form, the restraining means may be arranged to brake relativehorizontal movement between the roller and the drawbar. In thisarrangement, the restraining means may include a cam and followerarrangement, and a master cylinder and a slave cylinder interconnectedby a fluid line, the follower being arranged to actuate the mastercylinder, and the slave cylinder being arranged to actuate a brake.

Further according to the invention there is provided an impact rollerincluding a roller, a drawbar for attachment to a hauling vehicle, aresilient coupling between the drawbar and the roller to permit relativemovement between the roller and the drawbar, and restraining meansoperable between the roller and the drawbar to restrain relativehorizontal movement between the roller and the drawbar.

The roller may be rotatably mounted in or on the drawbar via anarticulated joint to permit rotation of the roller about a rotationalaxis.

Conveniently, the rotatable mounting of the roller may be arranged tohave a mid-operating position ahead of the articulated joint in thedirection of forward travel of the roller when the resilient coupling issubstantially in equilibrium with the roller during hauling of theroller. In this arrangement, the restraining means may be arranged torestrain relative horizontal movement between the roller and the drawbarwhen the horizontal movement fore and aft of the mid-operating positionexceeds one-fourth to three-fourths of the lift of the roller.

If desired, the restraining means may be arranged to permitsubstantially unrestrained horizontal movement between the roller andthe drawbar, except for the influence of the resilient coupling, whenthe relative horizontal movement is less than one-fourth tothree-fourths of the lift of the roller.

In one form, the restraining means may be arranged to damp relativehorizontal movement between the roller and the drawbar. In thisarrangement the restraining means may include a plunger and cylinderassembly between the drawbar and the roller, the plunger being arrangedto partition the cylinder into two chambers and to be displaced in thecylinder by relative movement between the roller and the drawbar todisplace a fluid under pressure from one chamber of the cylinder to theother via a restricted orifice to damp the movement of the plunger inthe cylinder.

Further in this form, there may be included a bell crank pivotallyinterconnecting the articulated joint, the roller at its rotatablemounting and one end of a plunger rod having at its other end theplunger, the cylinder being pivotally mounted on the drawbar. The bellcrank may be arranged to permit the plunger to obtain a top dead centerposition in the cylinder when the rotatable mounting of the roller is inits mid-operating position ahead of the articulated joint.

If desired, the substantially unrestrained horizontal movement over thepredetermined range may be effected by providing a lost motion couplingin the restraining means to permit initial lost motion before therestraining means becomes effective.

The resilient coupling may be provided inside the cylinder of therestraining means to form a unitary arrangement therewith, or it may beprovided as a unit separated from the restraining means.

In another form, the restraining means may be arranged to brake relativehorizontal movement between the roller and the drawbar. In this form,the restraining means may include a cam and follower arrangement, and amaster cylinder and a slave cylinder interconnected by a fluid line, thefollower being arranged to actuate the master cylinder, and the slavecylinder being arranged to actuate a brake.

The invention is now described by way of an example with reference tothe accompanying drawings, in which:

FIG. 1 shows a side view, partly in section, of an impact rollerincluding one embodiment of an hydraulic damping arrangement;

FIG. 2 shows a plan view, partly in section, of the roller shown in FIG.1;

FIG. 3 shows a view similar to FIG. 1 but with the roller includinganother embodiment of an hydraulic damping arrangement;

FIG. 4 shows yet another embodiment of an hydraulic damping arrangementsuitable for use on the roller shown in FIG. 1; and

FIG. 5 shows the impact roller of FIG. 1 with an hydraulic brakingarrangement.

Referring generally to FIGS. 1, 2 and 3 of the drawings, referencenumeral 10 indicates generally an impact roller including a roller 12 ofa non-circular cross-sectional profile. The roller 12 has an axle 14passing through its center of gravity 16.

The non-circular cross-sectional profile of the roller 12 includes fourrounded lobes 18 which cause the center of gravity 16 of the roller tointermittently rise and fall a distance (R-r) when the roller is hauledover the surface 20 to rotate in the direction of arrow 22. The fallingof the center of gravity delivers an impact to the surface 20, therebycausing compaction of the material underlying the surface 20. As thereare four lobes 18 on the roller, four blows are delivered during eachrevolution of the roller 12.

The roller axle 14 is attached to a drawbar 24 via bearings 26, tractionrods 28 secured to the bearings 26, and a resilient coupling comprisinga pair of leaf springs 30 secured at 32 to the drawbar 24 and via bolts34 to the traction rods 28. The drawbar 24 has a beam 36 on the end ofwhich may be secured a universal coupling for attachment to a haulingvehicle such as a tractor. It will be seen that during hauling, tractionforce is transmitted from the drawbar 24 via the springs 30, the bolts34, the traction rods 28 and the bearings 26 to the roller axle 14.

The drawbar 24 has two arms 40 extending rearwardly away from thedrawbar on either side of the roller 12 so that the roller is positionedbetween the arms. The end of each arm 40 vided a cylinder 46 and aplunger 48. Each cylinder 46 is pivotally connected to each arm 40 bymeans of a pin 50 and a bracket 52. The plunger 48 is mounted on aplunger rod 54 which is pivotally connected to the bell crank 42 bymeans of a pin 56 to be reciprocable in the cylinder 46.

The function of the plunger 48 and cylinder 46 is to restrain excessiverelative movement between the drawbar 24 and the roller 14 exceedingpredetermined limits by means of hydraulic damping.

The relative positions of the axle l4 and the pins 44 and 56 are soarranged that when the ins 44, 56 and 50 are all in line, the plunger 48reaches a top dead center position in the cylinder 46. In this positionthe plunger 48 can only be displaced from right to left in the cylinder46.

During normal operation of the roller 10, when the roller is beinghauled at a constant optimum speed in the direction of arrow 55 and theroller 12 rotates in the direction of arrow 22, a state of substantialequilibrium is reached between the springs 30 and the drag caused by themass of the roller 12. The optimum speed depends upon such factors asthe mass of the roller, the number of lobes on the roller and theresilience of the springs 30. In this position of equilibrium the rolleraxle 14 is disposed between the pin 44 and the drawbar 24 and theplunger 48 is in its top dead center position in the cylinder 46. Animaginary line 57 extending through the pin 44 and the axle 14 in thisposition can be regarded as the mid-operating position of the axle 14.

As soon as the hauling vehicle accelerates or decelerates, the inertiaof the roller 12 causes relative movement to take place between theroller axle l4 and the drawbar 24, i.e., the roller either lags behindor overruns the drawbar. This relative movement is normally essentialfor the operation of the roller, but is undesirable when it becomesexcessive under certain circumstances, particularly at slow speeds.These circumstances arise when the stored energy in the spring 30 whichtends to rotate the roller 12 in the direction of the arrow 22 is justinsufficient to pull the roller 12 over when it passes over a lobe 18.The roller then drops back in a direction opposite to arrow 22 and asthe hauling vehicle is still moving forward in the direction of arrow55, the roller and the hauling vehicle are momentarily moving inopposite directions, thereby causing a considerable relative movementbetween the roller and the drawbar 24. The relative movement isaccompanied by a shock force which may result in damage to the rollerstructure and cause wasteful dissipation of energy. The function of theplunger 48 and the cylinder 46 is to restrain these large relativemovements and thereby to dampen the accompanying shock forces.

rai

When a large relative movement occurs between the roller 12 and thedrawbar 24, the axle 14 is displaced from its midoperating position onthe line 57. Displacement takes place along a circular are 59 having itscenter of curvature on the axis of the pin 44. Displacement of the axle14 along the arch 59 can be in a clockwise or counterclockwisedirection. Whether the displacement of the axle 14 from itsmid-operating position on the line 57 is in clockwise orcounterclockwise direction, the arrangement as before described is suchthat the plunger 48 is displaced from right to left in the cylinder 46.

Referring now in particular to FIG. 1, the piston 48 partitions thecylinder 46 into two chambers 58 and 60 which are filled with anhydraulic fluid and which are in a closed hydraulic circuit with oneanother via fluid lines 62 and 64. In the fluid lines 62 and 64 areprovided devices 66 and 68 which permit unrestricted fluid flow in thedirections of the arrows but restricted flow in the opposite directions.A branch line 70 leads into an hydraulic fluid reservoir 72 foraccommodating and for making up fluid flow from and to the chambers 58and 60.

The plunger rod 54 has a shank 74 of a reduced cross-section for fittingin a bore through the plunger 48. The plunger 48 is secured on the shank74 between the plunger rod 54 and a nut 76. The spacing between the nut76 and the plunger rod 54 is such that some lost motion of the plunger48 is permitted on the shank 74 and the extent of the lost motion can bead justed by the nut 76. The effect of the lost motion is that a certainamount of substantially free movement is pennitted between the drawbaranns 40 and the roller 12 via the axle 14 and the plunger rod 54 beforethe plunger 48 is displaced.

When the plunger 48 is displaced in the cylinder 46, it displaceshydraulic fluid from one of the chambers 58 or 60 to the other via thedevices 66 and 68. Fluid flow through these devices against thedirection of the arrows is restricted, and consequently the movement ofthe plunger 48 in the cylinder 46 is restrained. In this manner,relative movement between the roller 12 and the drawbar 24 is damped.

Thus, while the lost motion effected by the shank 74 in the plunger 48permits minor undamped relative horizontal movement between the roller12 and the drawbar 24, major relative horizontal movements are damped.

In the arrangement shown in FIG. 1, the roller axle 14 is in itsmid-operating position on the line 57 and the plunger 48 is in its topdead center position in the cylinder 46. Consequently, the plunger rod54 will be displaced from right to left in the cylinder 46 regardless ofwhether the axle 14 is displaced clockwise or counterclockwise along theare 59.

Whenever the axle 14 is displaced along the are 59 from itsmid-operating position on line 57, it will move substantiallyunrestrained until the lost motion of the shank 74 in the plunger 48 isexhausted. As soon as the nut 76 abuts the plunger 48, dampingcommences. The angle of unrestrained movement of the axle 14 along theare 59 on either side of its mid-operating position is shown byreference numeral 78. The horizontal component of the portion of are 59intersected by twice angle 78 is shown by H. In other words, Hrepresents the limits of substantially unrestrained horizontal movementbetween the roller 12 and the drawbar 24. Relative movements between theroller and the drawbar exceeding these limits are damped.

Referring now in particular to FIG. 3, there is shown anotherarrangement for effecting hydraulic damping of relative horizontalmovement between the roller 12 and the drawbar 24. The drawing shows anarrangement of chambers 58, 60 and 62.1 and ports 64.1, 66.1, 68.1 and70.1 in the cylinder 46, and a passage 72.1 interconnecting the ports.The chambers 58 and 60 are filled with an hydraulic fluid, and thechamber 62.1 is partly filled with an hydraulic fluid and with a gasunder pressure.

The ports 66.1, 68.1 and 70.1 are comparatively large in size inrelation to the port 64.1 to permit unrestrained displacement ofhydraulic fluid through these ports. The port 64.1 is a restrictedorifice to retard the fluid flow through this port to restrain the axialdisplacement of the plunger 48 in the cylinder 46.

When the plunger 48 is between the ports 66.1 and 68.1, fluid can bedisplaced unrestrictedly between the chambers 58 and 60 via the ports66.1 and 68.1 and the passage 72.1 during small reciprocations of thepiston in the cylinder. Thus the movement of the piston in the cylinderis unrestrained as long as the piston is between the ports 66.1 and68.1.

During a large relative movement between the drawbar 24 and the axle 14,the piston 48 is displaced beyond the limits of ports 66.1 and 68.1.When the piston is displaced over port 66.1 towards the left as shown inFIG. 3, fluid is displaced from the chamber 58 via the restricted port64.1, the passage 72.1 and the port 68.1 to chamber 60. In view of therestricted fluid flow through the port 64.1, the movement of the piston48 in the cylinder 46 is restrained and thereby the movement of theroller 12 relative to the drawbar 24 is clamped.

The difference in volumes of fluid in the chambers 58 and 60 due to thevolume occupied by the plunger rod 54 is accommodated by displacementinto and out of the chamber 62.1 via port 70.1.

When the axle 14 is in its mid-operating position on line 57, theplunger 48 is in its top dead center position in the cylinder 46 betweenthe ports 66.1 and 68.1. As already described, the plunger can moveunrestrictedly in the cylinder 46 when it is between the ports 66.1 and68.1, i.e., the minor movements of the plunger are not restrained. Bybeing in its top dead center position the plunger 48 can only move fromright to left in the cylinder 46 and therefore never move over the port68.1.

The arrangement of the ports 64.1, 66.1 and 68.1 is such that the axle14 can move unrestrained along the are 59 for an angle 78 on either sideof its mid-operating position on line 57. The portion of are 59intersected by twice angles 78 has a horizontal component H. In otherwords, H represents the limits of substantially unrestrained horizontalmovement between the roller 12 and the drawbar 24. Outside these limitsthe plunger 48 moves over the port 66.1 towards the port 64.1 and itsmovement is restrained.

Referring now to FIG. 4 of the drawings, there is shown anotherhydraulic damping arrangement 80 for use with the impact roller shown inFIG. 1. The arrangement 80 is a combination in a single unit of thedamping piston and cylinder arrangement and the resilient couplingindicated in FIG. 1 by reference numerals 48, 46 and 30.

The arrangement 80 is pivotally secured between the drawbar 24 and theroller axle 14 of FIG. 1 by means of a bracket 82, a plunger rod 84 anda link 86 pivotally secured to the drawbar arm 40. On the plunger rod 84is mounted a plunger 88 which is axially displaceable in a cylinder 90in which it fits sealingly and which it divides into two sealed chambers92 and A compression spring 96 is mounted inside the chamber 92, and inaddition the chamber is filled with a gas. When the plunger 88 isdisplaced from right to left, it compresses the gas in the chamber 92and in addition compresses the spring 96. The compressed gas and thecompressed spring 96 form a resilient coupling between the roller axlel4 and the drawbar 24.

In the cylinder 90 there are provided two further chambers 98 and 100which are filled with an hydraulic fluid and which are in a closedhydraulic circuit with each other via an hydraulic line 102. Two pistons104 and 106 are slidably mounted on the plunger rod 84 to be sealinglydisplaceable into and out of the chambers 98 and 100. The relative axialpositions of the pistons 104 and 106 on the plunger rod 84 can beadjusted by screwing a plug 108 into or out of an hydraulic fluidreservoir 1 10.

The operation of arrangement 80 is as follows: During minor relativemovements between the roller axle 14 and the drawbar 24, the plunger 88is axially displaced in the cylinder 90 against the compression of thegas in the chamber 96 and the compression of the spring 96. The plunger88 under these conditions is displaced substantially unrestrained in thecylinder 90. As soon as the plunger 88 abuts the piston 104, furtherdisplacement of the plunger causes hydraulic fluid to be displaced fromthe chamber 98 via the line 102 to the chamber 100. In view of arestricted passage through the line 102, fluid flow through the line isretarded and consequently the displacement of the plunger 88 in thecylinder is damped. Fluid which is displaced from the chamber 98 tochamber displaces the piston 106 from right to left along the plungerrod 84.

It will be seen from the drawing that the displacement of the plunger 88in the cylinder 90 is substantially unrestrained between the pistons 104and 106, and these limits are indicated by H. Outside these limits theaxial displacement of the plunger 88 in the cylinder 90 is clamped andtherefore relative movement between the roller axle 14 and the drawbararm 40 causing such a displacement is restrained.

Referring now to FIG. 5 of the drawings, there is shown a brakingarrangement 112 for restraining relative horizontal movement between theaxle 14 of roller 12 shown in FIG. 1 and the drawbar 24. The axle 14 ispivotally secured to the drawbar arm 40 by means of a link 114 which hasa cranked stub axle 116. The stub axle 116 fits rotatably in a bush 118secured to the drawbar arm 40. A carrier 120 is fast with the stub axle1 16.

The carrier 120 has two arcuately spaced cams 122 and 124 whose relativearcuate positions on the carrier 120 are adjustable by means of bolts126 and 128 extending through arcuate slots 130 and 132. A follower 134co-operates with the cams 122 and 124 and is arranged to actuate anhydraulic fluid in a master cylinder 136. The master cylinder 136 via aline 138 and a slave cylinder 140 actuates a piston 142 to which isattached a brake block 144. When actuated, the brake block 144 abuts abrake drum 146 provided on the carrier 120 and brakes it frictionally.

Between the drawbar 24 and the axle 14 is provided a resilient couplingin the from of a spring 148 to transmit traction force from the drawbar24 to the roller axle 14 when the drawbar is pulled in the direction ofarrow 150. The roller 12 will then rotate in the direction of arrow 152.

When there is relative horizontal movement between the drawbar 24 andthe roller axle 14, the axle 14 is displaced along the are 59 (arc 59 isdescribed in more detail with reference to FIG. 1) about the crank 116.In other words, the stub axle 116 rotates in the bush 118, as a resultof which the carrier 120 is rotated. The carrier 120 can rotate betweenthe limits of cams 122 and 124 i.e., through an angle 154, withoutactuating the follower 134. Rotation of the carrier 120 exceeding theselimits will actuate the follower 134 and thereby the brake block 144,whereby the carrier 120 will be braked and relative movement between theroller axle 14 and the drawbar 24 will be restrained.

Consequently, substantially unrestrained horizontal movement between theroller axle l4 and the drawbar 24 will be permitted as long as themovement is such that the rotation of the carrier 120 is confined withinthe limits indicated above i.e., so that the follower 134 is notactuated.

The cams 122 and 124 are arcuately spaced from one another by the angle154 which is equal to twice the angle 78. Please refer to FIG. 1 for thedescription of angle 78 and line 57. Twice the angle 78 may betranslated into a horizontal component H. In other words, H representsthe limits of substantially unrestrained movement between the drawbar 24and the roller axle 14 before the brake parts 144 and 146 are actuated.

The impact delivered to the material underlying the surface 20 isdependent inter alia upon the lift of the center of gravity 16 i.e., thedistance (R-r). In order to affect the impact delivered as little aspossible, the distance H of unrestrained movement shown in FIGS. 1, 3, 4and 5, should be as large as possible. But the distance H should not betoo large, otherwise only an exceptional relative movement between theroller axle 14 and the drawbar 24 will be restrained. It is a practicalproblem to decide what the distance H should be. In practice it has beenfound that satisfactory results can be obtained by making the distance Hroughly equal to one-half of the lift of the roller i.e., H k (R-r),although it may vary from oneforth to three-fourths of the lift of theroller.

What i claim is:

1. Control means for controlling the movement of an impact roller havinga non-circular multi-lobe profile to obtain intermittent lift which isattachable to a hauling vehicle, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar to provide a resilient coupling therebetween and to permitrelative horizontal movement between the roller and the drawbar, thecontrol means including restraining means pivotally connected to theroller and the drawbar and operable by fluid pressure to restrainrelative horizontal movement between the roller and the drawbarexceeding one-fourth to three-fourths of the lift of the roller.

2. Control means according to claim 1, in which the restraining meansincludes a lost motioncoupling constituted by a plunger member slidablymounted on a plunger rod between spaced apart abutment portions thereonin a cylinder to permit substantially unrestrained horizontal movementbetween the roller and the drawbar, except for the influence of theresilient coupling when the relative horizontal movement is less thanone-fourth to three-fourths of the lift of the roller, and saidunrestrained horizontal movement is efiected in said lost motioncoupling before the restraining means becomes effective.

3. Control means according to claim 1, in which the restraining meansincludes a plunger and cylinder assembly attached between the roller andthe drawbar to damp relative horizontal movement therebetween, by actionof the plunger which is arranged to partition the cylinder into twochambers and to be displaced in the cylinder by relative movementbetween the roller and the drawbar to displace a fluid under pressurefrom one chamber of the cylinder to the other via a restricted orificeto damp the movement of the plunger in the cylinder.

4. An impact roller assembly having a non-circular multilobed profile toobtain intermittent lift including a roller, traction rod meansoperatively connected at one end to bearing means for said roller andconnected at the other end to resilient means which are operativelyconnected to a drawbar for attachment to a hauling vehicle, to provide aresilient coupling between the drawbar and the roller to permit relativehorizontal movement between the roller and the drawbar, and restrainingmeans pivotally connected to the roller and the drawbar by fluidpressure to restrain relative horizontal movement between the roller andthe drawbar exceeding onefourth to three-fourths of the lift of theroller.

5. An impact roller assembly according to claim 4, in which the rolleris rotatably mounted on the drawbar via an articulated joint to permitrotation of the roller about a rotational axis.

6. An impact roller assembly according to claim 5, in which therotatable mounting of the roller includes a mid-operating position aheadof the articulated joint in the direction of forward travel of theroller when the resilient coupling is substantially in equilibrium withthe roller during hauling of the roller and in which said restrainingmeans restrains relative horizontal movement between the roller and thedrawbar when the horizontal movement fore and aft of the mid-operatingposition exceeds one-fourth to three-fourths of the lift of the roller.

7. An impact roller assembly according to claim 4, in which therestraining means includes a lost motion coupling constituted by aplunger member slidably mounted on a plunger rod between spaced apartabutment portions thereon in a cylinder to permit substantiallyunrestrained horizontal movement between the roller and the drawbar,except for the influence of the resilient coupling, when the relativehorizontal movement is less than one-fourth to three-fourths of the liftof I amthe roller, and said unrestrained horizontal movement is effectedin said lost motion coupling before the restraining means becomesefi'ective.

8. An impact roller assembly according to claim 4, in which therestraining means comprises damping means to damp relative horizontalmovement between the roller and the drawbar.

9. An impact roller assembly having a non-circular multilobed profile toobtain intennittent lift including a roller, traction rod meansoperatively connected at one end to bearing means for said roller andconnected at the other end to resilient means which are operativelyconnected to a drawbar for attachment to a hauling vehicle, to provide aresilient coupling between the drawbar and the roller to permit relativehorizontal movement between the roller and the drawbar, and dampingmeans operable between the roller and the drawbar to damp relativehorizontal movement between the roller and the drawbar exceedingone-fourth to three-fourths of the lift of the roller, the damping meansincluding a plunger and cylinder assembly pivotally connected betweenthe drawbar and the roller, the plunger being arranged to partition thecylinder into two chambers and to be displaced in the cylinder byrelative movement between the roller and the drawbar to displace a fluidunder pressure from one chamber of the cylinder to the other via arestricted orifice to damp the movement of the plunger in the cylinder.

10. An impact roller assembly according to claim 9, which includes abell crank pivotally interconnecting the articulated joint, the rollerat its rotatable mounting and one end of a plunger rod having at itsother end the plunger, the cylinder being pivotally mounted on thedrawbar.

11 An impact roller assembly according to claim 10, in which the bellcrank is so constructed that the plunger obtains a top dead centerposition in the cylinder when the rotatable mounting of the roller is inits mid-operating position ahead of the articulated joint.

12. An impact roller according to claim 9, in which the resilientcoupling is provided inside the cylinder of the damping means.

13. Control means for controlling the movement of an impact rollerhaving a non-circular multi-lobed profile to obtain intermittent liftwhich is attachable to a hauling vehicle, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar to provide a resilient coupling therebetween to permit relativehorizontal movement between the roller and the drawbar, the controlmeans including frictional restraining means comprising brake meansoperable between the roller and the drawbar to frictionallyrestrain'relative horizontal movement between the roller and the drawbarexceeding one-fourth to threefourths of the lift of the roller.

14. Control means for controlling the movement of an impact rollerhaving a non-circular multi-lobed profile to obtain intermittent liftwhich is attachable to a hauling vehicle, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar to provide a resilient coupling therebetween to permit relativehorizontal movement between the roller and the drawbar, the controlmeans including brake means operable between the roller and the drawbarto brake relative horizontal movement between the roller and the drawbarexceeding one-fourth to three-fourths of the lift of the roller, thebrake means including a brake member, a cam and follower arrangement anda master cylinder and a slave cylinder interconnected by a fluid line,the follower being arranged to actuate the master cylinder and the slavecylinder being arranged to actuate the brake member 15. An impact rollerassembly having a non-circular multilobe profile to obtain intermittentlift including a roller, traction rod means operatively connected at oneend to hearing means for said roller and connected at the other end toresilient means which are operatively connected to a drawbar forattachment to a hauling vehicle, to provide a resilient coupling betweenthe drawbar and the roller to permit relative horizontal movementbetween the roller and the drawbar, and frictional restraining meansoperable between the roller and the drawbar to frictionally restrainrelative horizontal movement between the roller and the drawbarexceeding onefourth to three-fourths of the lift of the roller, saidrestraining means comprising brake means for braking relative horizontalmovement between the roller and the drawbar.

16. An impact roller assembly having a non-circular multilobed profileto obtain intermittent lift including a roller, traction rod meansoperatively connected at one end to bearing means for said roller andconnected at the other end to resilient means which are operativelyconnected to a drawbar for attachment to a hauling vehicle, to provide aresilient coupling between the drawbar and the roller to permit relativehorizontal movement between the roller and the drawbar, and brake meansoperable between the roller and the drawbar to brake relative horizontalmovement between the roller and the drawbar exceeding one-fourth tothree-fourths of the lift of the roller, the brake means including abrake member, a cam and follower arrangement and a master cylinder and aslave cylinder interconnected by a fluid line, the follower beingarranged to actuate the master cylinder and the slave cylinder beingarranged to actuate the brake member.

1. Control means for controlling the movement of an impact roller havinga non-circular multi-lobe profile to obtain intermittent lift which isattachable to a hauling vehicle, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar to provide a resilient coupling therebetween and to permitrelative horizontal movement between the roller and the drawbar, thecontrol means including restraining means pivotally connected to theroller and the drawbar and operable by fluid pressure to restrainrelative horizontal movement between the roller and the drawbarexceeding one-fourth to three-fourths of the lift of the roller. 2.Control means according to claim 1, in which the restraining meansincludes a lost motion coupling constituted by a plunger member slidablymounted on a plunger rod between spaced apart abutment portions thereonin a cylinder to permit substantially unrestrained horizontal movementbetween the roller and the drawbar, except for the influence of theresilient coupling when the relative horizontal movement is less thanone-fourth to three-fourths of the lift of the roller, and saidunrestrained horizontal movement is effected in said lost motioncoupling before the restraining means becomes effective.
 3. Controlmeans according to claim 1, in which the restraining means includes aplunger and cylinder assembly attached between the roller and thedrawbar to damp relative horizontal movement therebetween, by action ofthe plunger which is arranged to partition the cylinder into twochambers and to be displaced in the cylinder by relative movementbetween the roller and the drawbar to displace a fluid under pressurefrom one chamber of the cylinder to the other via a restricted orificeto damp the movement of the plunger in the cylinder.
 4. An impact rollerassembly having a non-circular multi-lobed profile to obtainintermittent lift including a roller, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar for attachment to a hauling vehicle, to provide a resilientcoupling between the drawbar and the roller to Permit relativehorizontal movement between the roller and the drawbar, and restrainingmeans pivotally connected to the roller and the drawbar by fluidpressure to restrain relative horizontal movement between the roller andthe drawbar exceeding one-fourth to three-fourths of the lift of theroller.
 5. An impact roller assembly according to claim 4, in which theroller is rotatably mounted on the drawbar via an articulated joint topermit rotation of the roller about a rotational axis.
 6. An impactroller assembly according to claim 5, in which the rotatable mounting ofthe roller includes a mid-operating position ahead of the articulatedjoint in the direction of forward travel of the roller when theresilient coupling is substantially in equilibrium with the rollerduring hauling of the roller and in which said restraining meansrestrains relative horizontal movement between the roller and thedrawbar when the horizontal movement fore and aft of the mid-operatingposition exceeds one-fourth to three-fourths of the lift of the roller.7. An impact roller assembly according to claim 4, in which therestraining means includes a lost motion coupling constituted by aplunger member slidably mounted on a plunger rod between spaced apartabutment portions thereon in a cylinder to permit substantiallyunrestrained horizontal movement between the roller and the drawbar,except for the influence of the resilient coupling, when the relativehorizontal movement is less than one-fourth to three-fourths of the liftof the roller, and said unrestrained horizontal movement is effected insaid lost motion coupling before the restraining means becomeseffective.
 8. An impact roller assembly according to claim 4, in whichthe restraining means comprises damping means to damp relativehorizontal movement between the roller and the drawbar.
 9. An impactroller assembly having a non-circular multi-lobed profile to obtainintermittent lift including a roller, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar for attachment to a hauling vehicle, to provide a resilientcoupling between the drawbar and the roller to permit relativehorizontal movement between the roller and the drawbar, and dampingmeans operable between the roller and the drawbar to damp relativehorizontal movement between the roller and the drawbar exceedingone-fourth to three-fourths of the lift of the roller, the damping meansincluding a plunger and cylinder assembly pivotally connected betweenthe drawbar and the roller, the plunger being arranged to partition thecylinder into two chambers and to be displaced in the cylinder byrelative movement between the roller and the drawbar to displace a fluidunder pressure from one chamber of the cylinder to the other via arestricted orifice to damp the movement of the plunger in the cylinder.10. An impact roller assembly according to claim 9, which includes abell crank pivotally interconnecting the articulated joint, the rollerat its rotatable mounting and one end of a plunger rod having at itsother end the plunger, the cylinder being pivotally mounted on thedrawbar.
 11. An impact roller assembly according to claim 10, in whichthe bell crank is so constructed that the plunger obtains a top deadcenter position in the cylinder when the rotatable mounting of theroller is in its mid-operating position ahead of the articulated joint.12. An impact roller according to claim 9, in which the resilientcoupling is provided inside the cylinder of the damping means. 13.Control means for controlling the movement of an impact roller having anon-circular multi-lobed profile to obtain intermittent lift which isattachable to a hauling vehicle, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar to proviDe a resilient coupling therebetween to permit relativehorizontal movement between the roller and the drawbar, the controlmeans including frictional restraining means comprising brake meansoperable between the roller and the drawbar to frictionally restrainrelative horizontal movement between the roller and the drawbarexceeding one-fourth to three-fourths of the lift of the roller. 14.Control means for controlling the movement of an impact roller having anon-circular multi-lobed profile to obtain intermittent lift which isattachable to a hauling vehicle, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar to provide a resilient coupling therebetween to permit relativehorizontal movement between the roller and the drawbar, the controlmeans including brake means operable between the roller and the drawbarto brake relative horizontal movement between the roller and the drawbarexceeding one-fourth to three-fourths of the lift of the roller, thebrake means including a brake member, a cam and follower arrangement anda master cylinder and a slave cylinder interconnected by a fluid line,the follower being arranged to actuate the master cylinder and the slavecylinder being arranged to actuate the brake member.
 15. An impactroller assembly having a non-circular multi-lobe profile to obtainintermittent lift including a roller, traction rod means operativelyconnected at one end to bearing means for said roller and connected atthe other end to resilient means which are operatively connected to adrawbar for attachment to a hauling vehicle, to provide a resilientcoupling between the drawbar and the roller to permit relativehorizontal movement between the roller and the drawbar, and frictionalrestraining means operable between the roller and the drawbar tofrictionally restrain relative horizontal movement between the rollerand the drawbar exceeding one-fourth to three-fourths of the lift of theroller, said restraining means comprising brake means for brakingrelative horizontal movement between the roller and the drawbar.
 16. Animpact roller assembly having a non-circular multi-lobed profile toobtain intermittent lift including a roller, traction rod meansoperatively connected at one end to bearing means for said roller andconnected at the other end to resilient means which are operativelyconnected to a drawbar for attachment to a hauling vehicle, to provide aresilient coupling between the drawbar and the roller to permit relativehorizontal movement between the roller and the drawbar, and brake meansoperable between the roller and the drawbar to brake relative horizontalmovement between the roller and the drawbar exceeding one-fourth tothree-fourths of the lift of the roller, the brake means including abrake member, a cam and follower arrangement and a master cylinder and aslave cylinder interconnected by a fluid line, the follower beingarranged to actuate the master cylinder and the slave cylinder beingarranged to actuate the brake member.